The different members of the human growth hormone family of proteins, including transcriptional variants and post-translational variants, and the diabetogenic factor will be characterized in regard to their different activities. Radioimmunoassays for each of these will be developed and radioreceptor assays will also be employed to distinguish them one from another, including sites of action. Their diverse effects on islet cell secretion and on endothelial cell growth, Factor VIII production and proteolytic activity will be studied. Pituitary factors will be studied for their effects on human endothelial cells in culture. Factor VIII differences in normal and in insulin-dependent and non-insulin dependent diabetics in relation to degree of control of glycemia and lipidemia will be pursued.